Outcome Analysis Of Preimplantation Genetic Testing For Chromosome Fusion Carriers

1 、 Effects of carrier’s sex and maternal age on the Preimplantation genetic testing results of Robertsonian translocations Objective:By sorting out the blastocyst results of preimplantation genetic testing of(PGT)in the carriers of Robertsonian translocation,the PGT outcome of Robertsonian translocation carriers was analyzed.To investigate the effects of a carrier’s sex and age on the Preimplantation genetic testing results and analyze whether the trivalent structure of the translocation affects the stability of the genome.To provide suggestions for reproductive genetic counseling of Robertsonian translocation.Methods:Data were collected from 763 couples with one of them is the Robertsonian translocation in CITIC-Xiangya Reproductive and Genetics Hospital.Their blastocyst trophoblast cells were analyzed by PGT-SR using the next generation sequencing(NGS),and the possible influencing factors such as age,sex of carriers and chromosomes involved were compared and statistically analyzed.Results:A total of 928 blastocyst cycles were carried out in 763 couples and3423 blastocysts were obtained.1728 transferable embryos were obtained,with a total of 760 cycles(81.9%).The results suggest that the carrier and the maternal age affected the PGT outcome.The proportion of cycles with transferable embryos in male carriers was significantly higher than that in female carriers(87.9% vs 76.5%,P<0.01).The main reason is that the alternate segregation rate of male Robertsonian translocation carriers is significantly higher than that of female carriers(82.3% vs 59.9%,P<0.01).The maternal age was divided into two groups:≤35 years old(young group)and > 35 years old(advanced maternal age,AMA group).The proportion of cycles with transferable embryos in the AMA group was significantly lower than that in the young group(62.5% vs 85%,P<0.01),mainly because the average number of biopsied embryos per cycle in the old group was much less than in the young group,while other chromosomal abnormalities were higher than those in the young group.Compared with the PGT-A control group,The results indicated that the proportion of chromosome mosaics in the Robertsonian translocation group was significantly increased(1.2% vs 0.5%,P<0.01).Conclusions:The carriers gender and maternal age had significant influence on the outcome of PGT.The proportion of transferable embryo cycle in different groups was as follows: young group male carriers(90%),young group female carriers(80.2%),AMA group male carriers(71.4%),and AMA group female carriers(56.9%).The trivalent structure will affect the stability of the genome during mitosis.2、Preimplantation genetic testing results of blastocysts from 12non-Robertsonian translocation carriers with chromosome fusion and comparison with Robertsonian translocation carriersObjective:To investigate the effects of non-Robertsonian translocation with chromosome fusion(N-RBCF)on their preimplantation embryos.Methods:Assisted reproduction with preimplantation genetic testing in chromosomal structural rearrangement(PGT-SR)we reperformed for of12 N-RBCF carriers.we analyzed the PGT-SR results of 12 N-RBCF carriers using next generation sequencing(NGS)and compared them with those derived from Robertsonian translocation carriers.Results:PGT was performed in 12 N-RBCF carriers,of which 4 carried Y-autosome fusions and 8 autosomal fusions.A total of 12(63.2%)out of19 blastocysts exhibited normal/balanced embryos and only one(5.3%)embryo exhibited unbalanced translocations among Y-autosome fusion cases.In contrast to these findings,the percentage of normal/balanced blastocysts in 8 autosomal N-RBCF cases was 28.2%(11/39),whereas the unbalanced translocation rate was 53.8%.Furthermore,the percentage of normal/balanced embryos in the Robertsonian translocation group was significantly higher than that of the 8 autosomal N-RBCF(48.7% vs28.2%)cases.The rates of abnormality from chromosomal fusion in the 8autosomal N-RBCF cases were significantly higher than those noted in the Robertsonian translocation(53.8% vs 31.4%)subjects.The results of the stratified analysis according to the carrier’s gender demonstrated that the rates of unbalanced translocation were significantly higher in the male autosomal N-RBCF subjects than those from the corresponding Robertsonian translocation(55% vs 19.7%)cases.Conclusion(s):A low number of unbalanced translocations was identified in blastocysts from N-RBCF subjects who carried the Y fusion.The risk of unbalanced translocation in autosomal N-RBCF was higher than that of the Robertsonian translocation notably in male carriers.